Multifunctional radio frequency systems and methods for uv sterilization, air purification, and defrost operations

ABSTRACT

Example systems have a defrost system that can receive a first RF signal at a first frequency to defrost a load. An air treatment device can receive a second RF signal at a second frequency and perform an air treatment process. An RF signal source has a power output, and a switching arrangement selectively electrically connects the defrost system and the first air treatment device to the power output of the RF signal source. A controller can electrically connect one of the defrost system and the first air treatment device to the power output of the RF signal source. When the defrost system is electrically connected, the RF signal source outputs the first RF signal at the first frequency, and when the first air treatment device is electrically connected, the RF signal source outputs the second RF signal at the second frequency.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of co-pending, U.S. patent applicationSer. No. 15/721,436, filed on Sep. 29, 2017.

TECHNICAL FIELD

Embodiments of the subject matter described herein relate generally tomultifunctional apparatuses and methods of using a single source ofradio frequency (RF) energy to selectively power different deviceswithin an appliance.

BACKGROUND

Large quantities of fresh food are wasted every year due to improper orinadequate storage. Storing food safely for a time while maintainingquality can usually be accomplished by storing the food at adequatelylow temperatures (e.g., below −18 degrees Celsius), by limiting thegrowth of bacteria that can spoil food, and by reducing the presence oforganic molecules that accelerate the aging of the food (e.g., acetone).To use food that is being preserved at low temperatures, time is neededto defrost the food by introduction of ambient heat, for example, beforeit can be cooked and/or consumed.

Adding functions to devices, such as the above functions related tostoring and using food, can be cost-prohibitive, as providing eachfunction separately requires additional costly equipment, and the addedequipment increases space requirements. In a food storage appliance suchas a refrigerator, for example, space used for equipment is notavailable for food, and the additional equipment increases the cost ofthe appliance. As a result, devices that add functions desired byconsumers tend to be larger and more costly.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the subject matter may be derived byreferring to the detailed description and claims when considered inconjunction with the following figures, wherein like reference numbersrefer to similar elements throughout the figures.

FIG. 1 is a perspective view of a refrigerator/freezer appliance thatincludes example embodiments of multifunctional systems;

FIG. 2 is a simplified block diagram of a multifunctional RF system, inaccordance with an example embodiment;

FIG. 3 is a flowchart of a method of operating a multifunctional RFsystem, in accordance with an example embodiment;

FIG. 4 is a flowchart of a method of operating a multifunctional RFsystem with a plasma generator, ultraviolet (UV) source, and defroster,in accordance with an example embodiment; and

FIG. 5 is a flowchart of a method of operating a multifunctional RFsystem with a plasma generator, UV source, and defroster, in accordancewith another example embodiment.

DETAILED DESCRIPTION

The following detailed description is merely illustrative in nature andis not intended to limit the embodiments of the subject matter or theapplication and uses of such embodiments. As used herein, the words“exemplary” and “example” mean “serving as an example, instance, orillustration.” Any implementation described herein as exemplary or anexample is not necessarily to be construed as preferred or advantageousover other implementations. Furthermore, there is no intention to bebound by any expressed or implied theory presented in the precedingtechnical field, background, or the following detailed description.

Appliances normally perform one function; for example, refrigeratorskeep food cold. Although appliances with additional functions aregenerally desirable for consumers, adding functionality tends to makeappliances substantially larger and more expensive. Embodiments of thesubject matter described herein relate to appliances incorporatingmultiple devices capable of performing different functions in smallerspaces and at lower costs than would be achievable using conventionaltechniques. As described in greater detail below, exemplary systems arerealized by using one radio frequency (RF) power source to powermultiple devices. The devices may include, for example: an RF defroster(e.g., to enable rapid defrosting from cold temperatures), anultraviolet (UV) light source (e.g., to limit the growth of bacteria),and a plasma source (e.g., to break down organic compounds in the air toslow the aging of food and eliminate unpleasant odors). A controlleradjusts the output of the RF power source to provide a frequency atwhich a selected device operates, and a switching arrangement directsthe output of the RF source to the selected devices. The devices canthus provide multiple functions using common equipment. An apparatus forperforming such functions (i.e., functions implemented using multipledevices) can be embodied as a standalone appliance, or can beincorporated into other systems (e.g., an appliance such as arefrigerator).

In some embodiments, one of the devices in the set of two or moredevices may be a solid-state defroster that can be realized using afirst electrode disposed in a cavity, an amplifier arrangement(including one or more transistors), an impedance matching networkcoupled between an output of the amplifier arrangement and the firstelectrode, and a measurement and control system that can detect when adefrosting operation has completed. In an embodiment, the impedancematching network is a variable impedance matching network that can beadjusted during the defrosting operation to improve matching between theamplifier arrangement and the cavity. As used herein, the term“defrosting” means a process by which the thermal energy or temperatureof a load (e.g., a food load or other type of load) is increased throughprovision of RF power to the load. Accordingly, in various embodiments,a “defrosting operation” may be performed on a load with any initialtemperature (e.g., any initial temperature below about 0 degreesCelsius), and the defrosting operation may be ceased at any finaltemperature that is higher than the initial temperature (e.g., includingfinal temperatures that are above or below 0 degrees Celsius).

Another potential device in the set may be a plasma source capable ofgenerating plasma. In certain embodiments, the plasma may be generatedusing, for example, a capacitively coupled plasma (CCP) source. A CCPsource may include metallic electrodes separated by a small distance,with one electrode connected to the RF power supply, and the otherelectrode grounded. When an electric field is generated between theelectrodes, atoms are ionized and release electrons. The electrons inthe gas are accelerated by the RF field and can ionize the gas directlyor indirectly by collisions, producing secondary electrons. When theelectric field is strong enough, it can lead to what is known aselectron avalanche. After avalanche breakdown, the gas becomeselectrically conductive due to abundant free electrons.

A third potential device in the set may be a gas-discharge lamp thatgenerates light by exciting plasma using RF power. In such lamps, awaveguide may be used to constrain and focus an electrical field intothe plasma. Free electrons accelerated by the electrical field collidewith gas and metal atoms. Electrons in the gas and metal atoms areexcited by these collisions, bringing the electrons to a higher energystate. Materials in the plasma lamp are selected such that when theelectrons fall back to their original (lower-energy) state, UV radiationis emitted.

Different combinations of devices can be incorporated in an appliance toachieve desired results depending on the specific application. Forexample, in certain embodiments, incorporating a UV source and a plasmasource with a common RF power source can be useful for airpurification/cleaning, as UV light inhibits growth of microorganismslike bacteria, and plasma reduces unpleasant odors by breaking downodor-causing molecules. Such an air purification system may purify airin, for example, a house, an office building, a health care facility(such as a hospital or clinic), a vehicle (personal or commercial), etc.In other embodiments, a plasma source and a defroster (with an RF powersource) may be incorporated into an appliance. This pairing of devicesmay be useful in, for example, a refrigerator, allowing a user todefrost foods using the defroster, and to slow aging of food and reduceodors that may result from the defrost process by using plasma to breakdown organic molecules. In yet other embodiments, a UV source mayadditionally be incorporated in, for example, a refrigerator (orstandalone appliance) that includes a defroster and plasma sourcesharing an RF power source, so as to provide anti-microbialfunctionality through irradiation with UV light.

FIG. 1 is a perspective view of a refrigerator/freezer appliance 100 inwhich two or more devices sharing an RF power generator may beincorporated. More specifically, a multifunctional system 110 is shownto be incorporated within a freezer compartment 112 of the system 100,and multifunctional system 120 is shown to be incorporated within arefrigerator compartment 122 of the system 100. An actualrefrigerator/freezer appliance likely would include only one of themultifunctional systems 110, 120, but both are shown in FIG. 1 toconcisely convey both embodiments. Each of multifunctional systems 110,120 includes a heating cavity (inside of compartment 112, 122,respectively), and a control panel 114, 124. For example, the cavity maybe defined by interior surfaces of bottom, side, front, and back wallsof a drawer, and an interior top surface of a fixed shelf 116, 126 underwhich the drawer slides. With the drawer slid fully under the shelf, thedrawer and shelf define the cavity as an enclosed air cavity. As usedherein, the term “air cavity” may mean an enclosed area that containsair or other gases.

In the case of multifunctional systems with defrosters, a firstelectrode (e.g., electrode 270, FIG. 2) may be arranged proximate to acavity wall, with the first electrode electrically isolated from theremaining cavity walls, and with the remaining cavity walls grounded. Inother system implementations, multiple electrodes may be incorporatedinto a defrosting system in which an electric potential is establishedacross the multiple electrodes to warm a food load therein. In such aconfiguration, the defroster may be simplistically modeled as acapacitor, where the first electrode functions as one conductive plate,the grounded cavity walls function as a second conductive plate (orelectrode), and the air cavity (including any load contained therein)function as a dielectric medium between the first and second conductiveplates. According to an embodiment, during operation of themultifunctional system 100, a user (not illustrated) may place one ormore loads (e.g., food and/or liquids) into the defrosting cavity, andoptionally may provide inputs via the control panel 114, 124 thatspecify characteristics of the load(s), such as an approximate weight ormaterial of the load. In addition, the specified load characteristicsmay indicate the material(s) from which the load is formed (e.g., meat,bread, liquid). In alternate embodiments, the load characteristics maybe obtained in some other way, such as by scanning a barcode on the loadpackaging or receiving a radio frequency identification (RFID) signalfrom an RFID tag on or embedded within the load. Either way, informationregarding such load characteristics enables a system controller (e.g.,system controller 230, FIG. 2) to establish an initial state for theimpedance matching network of the system at the beginning of thedefrosting operation, where the initial state may be relatively close toan optimal state that enables maximum RF power transfer into the load.Alternatively, load characteristics may not be entered or received priorto commencement of a defrosting operation, and the system controller mayestablish a default initial state for the impedance matching network.

The system controller causes the RF signal source(s) (e.g., RF signalsource 240, FIG. 2) to supply an RF signal to the first electrode, whichresponsively radiates electromagnetic energy into a defrosting cavity ofa multifunctional system 110, 120. The electromagnetic energy increasesthe thermal energy of the load (i.e., the electromagnetic energy causesthe load to warm up). During the defrosting operation, the impedance ofthe load (and thus the total input impedance of the cavity plus load)changes as the thermal energy of the load increases. The impedancechanges alter the absorption of RF energy into the load, and thus alterthe magnitude of reflected power. According to an embodiment, powerdetection circuitry (e.g., power detection circuitry 278, FIG. 2)continuously or periodically measures the forward and/or reflected poweralong a transmission path (e.g., transmission path 248, FIG. 2) betweenthe RF signal source (e.g., RF signal source 240, FIG. 2) and the firstelectrode. Based on these measurements, the system controller (e.g.,system controller 230, FIG. 2) may detect completion of the defrostingoperation. According to a further embodiment, the impedance matchingnetwork is variable, and based on the forward and/or reflected powermeasurements, the system controller may alter the state of the impedancematching network during the defrosting operation to increase theabsorption of RF power by the load.

Those of skill in the art would understand, based on the descriptionherein, that embodiments of defrosting systems may be incorporated intomultifunctional systems or appliances having other configurations, aswell. Accordingly, the above-described implementations ofmultifunctional systems in a stand-alone appliance, a freezer, and arefrigerator are not meant to limit use of the embodiments only to thosetypes of systems. Although multifunctional systems 110, 120 are shownwith their components in particular relative orientations with respectto one another, it should be understood that the various components maybe oriented differently, as well. In addition, the physicalconfigurations of the various components may be different. For example,control panels 114, 124 may have more, fewer, or different userinterface elements, and/or the user interface elements may bedifferently arranged. In addition, although a substantially cubic cavityis indicated in FIG. 1, it should be understood that a defrosting cavitymay have a different shape, in other embodiments (e.g., cylindrical, andso on). Further, defrosting systems within the multifunctional systems110, 120 may include additional components (e.g., a fan, a stationary orrotating plate, a tray, an electrical cord, and so on) that are notspecifically depicted in FIG. 1 or elsewhere in the drawings.

Various multifunctional system embodiments incorporate devices which may(or may not) be co-located with each other. FIG. 2 is a simplified blockdiagram of a multifunctional system 200 (e.g., multifunctional system110, 120, FIG. 1), in accordance with an example embodiment.Multifunctional system 200 includes defrosting cavity 210, userinterface 220, system controller 230, RF signal source 240, power supplyand bias circuitry 250, variable impedance matching network 260,electrode 270, and power detection circuitry 278, in an embodiment. Inaddition, in other embodiments, multifunctional system 200 may include aplasma electrode used as part of a plasma generator 280 in an airpurification chamber 282. Multifunctional system 200 may also includeone or more UV tubes used as part of a UV source 290, which may also belocated in the air purification chamber 282 in certain embodiments, ormay be located within a separate chamber (not pictured). In variousembodiments, UV source 290 may include a filament disposed with atransparent (e.g., glass) tube. Such a UV source 290 may beelectrodeless and so may not incorporate metal contacts at either end ofthe transparent tube. According to an embodiment, one or more open orbaffled openings may be present between the defrosting cavity 210 andthe air purification chamber 282 so that air may be exchanged betweenthe cavity 210 and the chamber 282. In other embodiments, the system maybe configured so that the air purification chamber 282 also oralternatively may exchange air with other system spaces (e.g., theinteriors of a refrigerator and/or freezer compartment 112, 122).

In certain embodiments, one or more fans 295 are located in (or areotherwise in fluid communication with) the air purification chamber 282and/or the cavity 210. The fan 295 may be used to circulate air toeffect air exchange between the air purification chamber/cavity and thesurrounding ambient air (e.g., air in the interior refrigerator and/orfreezer compartments 112, 122). For example, plasma may be generatedusing plasma electrodes of a plasma generator 280, and UV light may beemitted using UV tubes of a UV source 290, for application of plasma andUV light to air in the air purification chamber 282. In an embodiment,plasma generator 280 and UV source 290 may share the same housing. Thefan 295 may then exchange the air treated with plasma and/or UV light inthe air purification chamber with, for example, air outside of the airpurification chamber 282, such as air in the cavity 210 or air in theappliance (standalone or otherwise) that includes multifunctional system200. In various embodiments, the fan 295 may be controlled by the systemcontroller 230 (such that the fan 295 is turned on, or its speed varied,by the system controller 230 based on, for example, the timing of plasmageneration and/or UV light irradiation). In other embodiments, the fan295 may be controlled by (independently or in conjunction with) acontroller of an appliance into which the multifunctional system 200 isincorporated. For example, a controller of a refrigerator may run thefan 295 according to a schedule that may be independent of, orcoordinated with, a schedule for application of plasma and/or UV light.

It should be understood that FIG. 2 is a simplified representation of amultifunctional system 200 for purposes of explanation and ease ofdescription, and that practical embodiments may include other devicesand components to provide additional functions and features, and/or themultifunctional system 200 may be part of a larger electrical system. Inother embodiments, for example, multifunctional system 200 may have aplasma generator 280 (e.g., plasma generator 280, FIG. 2) and UV source290 (e.g., UV source 290, FIG. 2), but no defroster. Alternatively, insome embodiments, the multifunctional system 200 may include a defrosterwith either a plasma generator or a UV source (but not both).

User interface 220 may correspond to a control panel (e.g., controlpanel 114, 124, FIG. 1), for example, which enables a user to provideinputs to the system regarding parameters for a defrosting operation(e.g., characteristics of the load to be defrosted, and so on), a plasmageneration operation (e.g., duration and timing of plasma generation), aUV source operation (e.g., timing and intensity of UV light), start andcancel buttons, mechanical controls (e.g., a door/drawer open latch),and so on. In addition, the user interface 220 may be configured toprovide user-perceptible outputs indicating the status of a defrostingoperation (e.g., a countdown timer, visible indicia indicating progressor completion of the defrosting operation, and/or audible tonesindicating completion of the defrosting operation) and otherinformation.

System controller 230 may include one or more general purpose or specialpurpose processors (e.g., a microprocessor, microcontroller, ApplicationSpecific Integrated Circuit (ASIC), and so on), volatile and/ornon-volatile memory (e.g., Random Access Memory (RAM), Read Only Memory(ROM), flash, various registers, and so on), one or more communicationbusses, and other components. According to an embodiment, systemcontroller 230 is coupled to user interface 220, RF signal source 240,variable impedance matching network 260, power detection circuitry 278,plasma generator 280, UV source 290, and fan 295. System controller 230is configured to receive signals indicating user inputs received viauser interface 220, and to receive forward and/or reflected powermeasurements from power detection circuitry 278. Responsive to thereceived signals and measurements, system controller 230 providescontrol signals to the power supply and bias circuitry 250 and to the RFsignal generator 242 of the RF signal source 240. In addition, systemcontroller 230 provides control signals to the variable impedancematching network 260, which causes the matching network 260 to changeits state or configuration.

A switching arrangement 265 is configured to selectively connect theoutput of RF signal source 240 to the defroster (e.g., to electrode270), the plasma generator 280 (e.g., plasma generator 280 includingplasma electrodes), and the UV source 290 (e.g., UV source 290 includingUV tubes). The devices powered using RF signal source 240 may requirecertain frequencies (i.e., be designed to operate using RF signals withfrequencies falling in different frequency bands), and the systemcontroller 230 may direct the RF signal generator 242 to generate RFsignals with frequencies suited to the device being powered using the RFsignal source 240. The switching arrangement 260 may be instructed toswitch to another device as specified by the system controller 230. Inother embodiments, if the devices are operated at different frequencies(e.g., within non-overlapping frequency bands), the switchingarrangement may detect the RF frequency being provided by the RF signalsource 240 (as directed by system controller 230) and switch to thedevice which operates at that corresponding frequency. When switchingthe RF signal source 240 between devices (e.g., UV source 240, plasmagenerator 208, and electrode 270), the RF signal source 240 may beconfigured to reduce a power of an RF signal outputted by RF signalsource 240 which may, in turn, reduce the likelihood of potential damageto the switching arrangement as well as reducing the creation oftransient signal at the time of switching. After the switchingarrangement has connected the desired device (e.g., plasma generator208, UV source 240, or electrode 270) to the RF signal source 240, thepower of the signal outputted by RF signal source 240 can against beincreased.

The first electrode 270 is electrically coupled to the RF signal source240 through a variable impedance matching network 260 and a transmissionpath 248, in an embodiment. The variable impedance matching circuit 260is configured to perform an impedance transformation from an impedanceof the RF signal source 240 to an input impedance of defrosting cavity210 as modified by a load in the cavity 210. In an embodiment, thevariable impedance matching network 260 includes a network of passivecomponents (e.g., inductors, capacitors, resistors). According to a morespecific embodiment, the variable impedance matching network 260includes a plurality of fixed-value lumped inductors that are positionedwithin the cavity 210 and which are electrically coupled to the firstelectrode 270. In addition, the variable impedance matching network 260includes a plurality of variable inductance networks, which may belocated inside or outside of the cavity 210. The inductance valueprovided by each of the variable inductance networks is establishedusing control signals from the system controller 230. In any event, bychanging the state of the variable impedance matching network 260 overthe course of a defrosting operation to dynamically match theever-changing cavity input impedance, the amount of RF power that isabsorbed by the load may be maintained at a high level despitevariations in the load impedance during the defrosting operation.

System 200 also provides impedance matching for the plasma electrodes ofthe plasma generator 280 and UV tubes of the UV source 290, but theinput impedances of these devices do not necessarily fluctuate in thesame way as the defroster (which includes a load with an impedance thatmay change significantly as it is heated). For devices with inputimpedances that are relatively stable over time, a variable impedancematching network may not be necessary. For example, the input impedancesof the plasma electrodes of the plasma generator 280 and UV tubes of theUV source 290 may stay fairly static over time. Consequently, animpedance of the RF signal source 240 is matched to an impedance of theplasma electrodes or the UV tubes when one of the corresponding devicesis to be operated.

According to an embodiment, RF signal source 240 includes an RF signalgenerator 242 and a power amplifier (e.g., including one or more poweramplifier stages 244, 246). In response to control signals provided bysystem controller 230, RF signal generator 242 is configured to producean oscillating electrical signal having a desired frequency. The RFsignal generator 242 may be controlled to produce oscillating signals ofdifferent power levels and/or different frequencies, in variousembodiments. For example, the RF signal generator 242 may produce asignal that oscillates in a range of about 3.0 megahertz (MHz) to about300 MHz. Some desirable frequencies may be, for example, 13.56 MHz (+/−5percent), 27.125 MHz (+/−5 percent), and 40.68 MHz (+/−5 percent). In anembodiment, the plasma generator, for example, may be driven by an RFsignal, produced by the RF signal generator 342, with a frequency ofabout 13.56 MHz, and a power level in a range of about 1 W to 5 kW,though in some embodiments the power level may be in the range of 1-20W. In another embodiment, for example, the RF signal generator 342 mayproduce a signal that oscillates in a range of about 40.66 MHz to about40.70 MHz and at a power level in a range of about 1 W to 5 kW for useby the defroster. In yet another embodiment, for example the RF signalgenerator 342 may be controlled to produce a signal with a power levelin a range of about 1 W to about 20 W or higher for use by the UV tubesof UV source 290. Alternatively, the frequencies of oscillation and/orthe power levels may be lower or higher. For example, when supplying asignal to only UV source and plasma generator the RF signal generator342 may provide a signal having a frequency that ranges from 1 MHz up to10 gigahertz (GHz). When supplying a signal to the UV source, plasmagenerator, and the heating electrode, for example, the RF signalgenerator 342 may provide a signal having a frequency that ranges from 1MHz up to 1 GHz, for example. Either way, the above examples indicatethat the RF signal generator 342 and the amplifier stages 244, 246 maybe controlled (e.g., by system controller 230) to provide an RF signalto the switching arrangement 265 that may have a different frequencyand/or different power level depending on whether the switchingarrangement 265 is providing the signal to the defroster, to the plasmagenerator 280 or to the UV source 290.

In the embodiment of FIG. 2, the power amplifier includes a driveramplifier stage 244 and a final amplifier stage 246. The power amplifieris configured to receive the oscillating signal from the RF signalgenerator 242, and to amplify the signal to produce a significantlyhigher-power signal at an output of the power amplifier. For example,the output signal may have a power level in a range of about 100 wattsto about 400 watts or more, although the output signal may have a lowerpower level, as well. The gain applied by the power amplifier may becontrolled using gate bias voltages and/or drain supply voltagesprovided by the power supply and bias circuitry 250 to each amplifierstage 244, 246. More specifically, power supply and bias circuitry 250provides bias and supply voltages to each RF amplifier stage 244, 246 inaccordance with control signals received from system controller 230.

In an embodiment, each amplifier stage 244, 246 is implemented as apower transistor, such as a field effect transistor (FET), having aninput terminal (e.g., a gate or control terminal) and two currentcarrying terminals (e.g., source and drain terminals). Impedancematching circuits (not illustrated) may be coupled to the input (e.g.,gate) of the driver amplifier stage 244, between the driver and finalamplifier stages 246, and/or to the output (e.g., drain terminal) of thefinal amplifier stage 246, in various embodiments. In an embodiment,each transistor of the amplifier stages 244, 246 includes a laterallydiffused metal oxide semiconductor FET (LDMOSFET) transistor. However,it should be noted that the transistors are not intended to be limitedto any particular semiconductor technology, and in other embodiments,each transistor may be realized as a gallium nitride (GaN) transistor,another type of MOSFET transistor, a bipolar junction transistor (BJT),or a transistor utilizing another semiconductor technology.

In FIG. 2, the power amplifier arrangement is depicted to include twoamplifier stages 244, 246 coupled in a particular manner to othercircuit components. In other embodiments, the power amplifierarrangement may include other amplifier topologies and/or the amplifierarrangement may include only one amplifier stage, or more than twoamplifier stages. For example, the power amplifier arrangement mayinclude various embodiments of a single ended amplifier, a double endedamplifier, a push-pull amplifier, a Doherty amplifier, a Switch ModePower Amplifier (SMPA), or another type of amplifier.

Power detection circuitry 278 may be coupled along the transmission path248 between the output of the RF signal source 240 and the input to theswitching arrangement 265, in various embodiments. In an alternateembodiment, power detection circuitry 278 may be coupled to thetransmission path 249 between the output of the matching network 260 andthe first electrode 270. Either way, power detection circuitry 278 isconfigured to monitor, measure, or otherwise detect the power of theforward signals (i.e., from RF signal source 240 toward first electrode270) and/or the reflected signals (i.e., from first electrode 270 towardRF signal source 240) traveling along the transmission path 248.

Power detection circuitry 278 supplies signals conveying the magnitudesof the forward and reflected signal power to system controller 230.System controller 230, in turn, may calculate a ratio of reflectedsignal power to forward signal power, or the S11 parameter. When thereflected power exceeds a threshold or the reflected to forward powerratio exceeds a threshold, this indicates that the system 200 is notadequately matched, and that energy absorption by the load may besub-optimal. In such a situation, system controller 230 orchestrates aprocess of altering the state of the variable impedance matching networkuntil the reflected power or the reflected to forward power ratiodecreases to a desired level, thus re-establishing an acceptable matchand facilitating more optimal energy absorption by the load.

Some embodiments of multifunctional system 200 may include temperaturesensor(s), IR sensor(s), and/or weight sensor(s) to provide data to thesystem controller 230. Information from the sensors (e.g., temperatureinformation) enables the system controller 230 to alter the power of theRF signal supplied by the RF signal source 240 (e.g., by controlling thebias and/or supply voltages provided by the power supply and biascircuitry 250), to adjust the state of the variable impedance matchingnetwork 260, and/or to determine when the operations (e.g., defrosting)should be terminated. The weight sensor(s) may be positioned under theload, and are configured to provide an estimate of the weight of theload to the system controller 230, which may use the weight information,for example, to determine a desired power level for the RF signalsupplied by the RF signal source 240, to determine an initial settingfor the variable impedance matching network 260, and/or to determine anapproximate duration for the defrosting operation.

According to an embodiment, the variable impedance matching network 260may include a network of passive components, and more specifically anetwork of fixed-value inductors (e.g., lumped inductive components) andvariable inductors (or variable inductance networks). As used herein,the term “inductor” means a discrete inductor or a set of inductivecomponents that are electrically coupled together without interveningcomponents of other types (e.g., resistors or capacitors).

Various embodiments of methods for operating such multifunctionalsystems will now be described in conjunction with FIG. 3. Morespecifically, FIG. 3 is a flowchart of a method of operating amultifunctional system (e.g., system 200, FIG. 2), in accordance with anexample embodiment. The method may begin, in block 302, when the systemcontroller (e.g., system controller 230, FIG. 2) receives an indicationthat a new operation (e.g., defrosting, plasma generation, or UVirradiation) should start. Such an indication may be received, forexample, after a user has placed a load into a defrosting cavity (e.g.,cavity 210, FIG. 2), has sealed the cavity (e.g., by closing a door ordrawer), and has pressed a start button (e.g., of the user interface220, FIG. 2). Such an indication may also be based on a predeterminedschedule provided to, or saved by, the system controller, such asgeneration of plasma or UV light at certain times or with a certainfrequency (e.g., at midnight, once per hour, etc.). Alternatively, suchan indication may also be based on the occurrence of another triggeringevent, such as the completion of a defrosting operation, an air qualitymeasurement within the cavity crossing a threshold, a temperature of thecavity crossing a threshold, the opening or closing of a door or drawer,and so on.

In block 304, if an operation is currently being performed by a device(i.e., if an operation is “in-process”), the system controller may waitfor the in-process operation to complete. For example, if the in-processoperation is defrosting a load, the system controller may wait for thedefrost operation to complete. Alternatively, the system controller maywait for a sub-process of the in-process operation to complete. Forexample, if a defrost operation involves alternating between thesub-processes of energizing an electrode for a time (e.g., five minutes)and pausing energizing the electrode for a time (e.g., five minutes),the system controller may wait for a pause between repeatingenergizations (e.g., the system controller may wait for one sub-processto complete). In other embodiments, the system controller may wait apredetermined/preset time (e.g., one minute) to allow an in-processoperation (such as UV irradiation) to continue for a time before it isstopped. In other embodiments, the system controller may pause anin-process operation, then resume the paused operation after the newoperation is completed. Alternatively, the system controller mayalternate between the paused operation and the new operation. In yetother embodiments, an in-process operation may be canceled if a newoperation is to be performed. The canceled operation may be performedlater according to a new user command, preset schedule, or triggeringevent.

In block 306, if the new operation is to be performed using a device notalready selected for being powered by the RF power generator (i.e., theswitching arrangement is not already configured to provide the RF signalto the device), the system controller (e.g., system controller 230) mayprovide a control signal to cause the switching arrangement (e.g.,switching arrangement 265) to change (switch) from an idle state or fromproviding the RF signal generated by the RF signal source (e.g., RFsignal source 240) to a device used to perform a previous/in-processoperation, to providing the RF signal to another (new) device to be usedto perform the new operation. This may involve adjusting the RFfrequency produced by the RF signal generator to an operationalfrequency for the new device, as needed. In block 308, the device nowbeing powered by the RF power source (i.e., the device now beingprovided the RF signal) is engaged to perform the new operation. Morespecifically, one or more control signals may be provided to the newdevice to cause the device to convert or consume the RF signal, asappropriate, to excite the electrodes (e.g., electrode 270 or theelectrode(s) of the plasma generator 280) or tubes (e.g., the UV tubesof the UV source 290) in order to perform the intended function of thedevice. The operation then continues until a start indication isreceived for a new operation (block 304), or until the operationcompletes (e.g., a timeout occurs, completion of the operation isdetected, the operation is interrupted, or another event triggeringoperation cessation occurs). It should be understood that the order ofoperations associated with the blocks depicted in FIG. 3 corresponds toan example embodiment, and should not be construed to limit the sequenceof operations only to the illustrated order. Instead, some operationsmay be performed in different orders, and/or some operations may beperformed in parallel.

FIG. 4 is a flowchart of a method of operating a multifunctional systemwith a plasma generator (e.g., plasma generator 280), UV source (e.g.,UV source 290), and defroster (e.g., including matching network 260 andelectrode 270), in accordance with an example embodiment. In block 402,a controller of the multifunctional system (e.g., system controller 230)may send control signals to operate the plasma generator and UV sourceaccording to a predetermined schedule (which may be, e.g., factorypreset, or programmed by a user). For example, the system controller maysend control signals to the switching arrangement (e.g., switchingarrangement 265) to provide an RF signal to the plasma generator (and tothe plasma electrodes), and control signals to the plasma generator togenerate plasma for a period of time (e.g., one minute each hour, orsome other time period based on a triggering event). At different times,the system controller may send control signals to the switchingarrangement to provide an RF signal to the UV source (and to the UVtubes), and control signals to the UV source to generate UV light for aperiod of time (e.g., five minutes each hour, or some other time periodbased on a triggering event). The system controller may schedule a breakbetween plasma and UV operations. Each time the plasma generator is tobe activated, the frequency and impedance of the RF signal source (e.g.,RF signal source 240) are adjusted to correspond with the operationalfrequency and impedance of the plasma generator, and the switchingarrangement connects the output of the RF signal source to the plasmagenerator, in certain embodiments. Similarly, each time the UV source isto be activated, the frequency and impedance of the RF signal source areadjusted to correspond with the operational frequency and impedance ofthe UV source, and the switching arrangement connects the output of theRF signal source to the UV source, in certain embodiments. In otherembodiments, one or both of the plasma generator and UV source mayalternatively or additionally also be operated upon a user command(received via a user interface) or based on another triggering event.Further, although an embodiment includes operating the plasma generatorand UV source during non-overlapping time periods, other embodiments mayinclude simultaneous operation of the plasma generator and UV source.

In block 404, the system controller determines whether a command toinitiate a defrost operation is received (e.g., from a user through theuser interface, or as a result of a prescheduled defrost operation).This determination may be performed repeatedly between plasma and UVgeneration operations, in certain embodiments, or may be made based onan interrupt. In other embodiments, the check may be performed morefrequently (e.g., during plasma and UV generation operations, in whichcase the plasma/UV operation may be, e.g., paused or canceled, asdiscussed above), or less frequently (e.g., once every 20 seconds on aperiodic basis, or once every 20 seconds only between plasma and UVgeneration operations). If no defrost initiation command is received(404), the system controller continues with its scheduled plasma and UVgeneration operations (402). When a defrost command is received (404),then in block 406, the system controller causes the switchingarrangement to connect the defroster (e.g., matching network 260 andelectrode 270) to the output of the RF signal source (e.g., RF signalsource 240). In block 408, the RF signal source is used to power thedefroster, and a variable impedance matching network (e.g., matchingnetwork 260) is used to match RF signal source and defroster impedances,as discussed above. In block 410, when the defrost operation hascompleted (which may be determined based on a temperature and/orimpedance of the load, for example), the system controller may return toproviding control signals to perform the plasma and UV generationoperations (402). When the defrost operation has not completed, the RFsignal source continues to power the defroster, and the variableimpedance matching network continues to match impedances until thedefrost operation is completed.

In alternative embodiments, the defrost operation may be interrupted(paused) to allow, for example, scheduled plasma and/or UV operations tobe performed. In such embodiments, when a defrost operation is to bepaused for a plasma operation, the plasma generator is powered until theplasma operation is completed; similarly, when a defrost operation is tobe paused for a UV operation, the UV generator is powered until the UVoperation is completed. Once the plasma/UV operation has been performed,the defroster may be powered to resume the defrosting operation.

FIG. 5 is a flowchart of a method of operating a multifunctional systemwith a plasma generator, UV source, and defrost system, in accordancewith another example embodiment. The method involves a default loop(502) and a defrost/cooking loop (504). The default loop (502) involvesusing a plasma generator and UV source to purify air according to apredetermined schedule, until air purification is interrupted (505) by apreset schedule or user command for a defrost operation, at which timethe defrost/cooking loop (504) is executed until the defrost operationhas completed, is interrupted, or has otherwise run its course.

In block 506, the system controller sends control signals to theswitching arrangement to connect the plasma generator to the RF signalsource. Next, in block 508, the system controller may send controlsignals to activate a fan (e.g., fan 295) so that air treated with theplasma can be circulated through an air purification chamber/appliance.In block 510, the system controller sends control signals to the RFsignal source to set the output signal produced by the RF signal sourceto a frequency required by the plasma generator. The RF signal sourceprovides an RF signal to the plasma generator for a certain period oftime (according to a preset schedule) until, in block 512, the systemcontroller sends control signals to the switching arrangement todisconnect the plasma generator from the RF signal source. In block 514,the system controller sends control signals to the switching arrangementto connect the UV source to the RF signal source and, in block 516, thesystem controller sends additional control signals to the RF signalsource to set the output signal produced by the RF signal source to afrequency required by the UV source. The system controller may cause theRF signal source to provide an RF signal to the UV source for a certainperiod of time (according to a preset schedule) until, in block 518, thesystem controller sends control signals to the switching arrangement todisconnect the UV source from the RF signal source. The default loopprocess then repeats by looping back to block 506, allowing the systemcontroller again to operate the plasma generator based on the presetschedule. It is noted that the default loop (502) may alternativelybegin by connecting the UV source to the RF signal source, or byactivating the fan, instead of connecting the plasma generator to the RFpower source. In other words, the order of operations in the defaultloop may be different from that depicted in FIG. 5.

When an interrupt (505) occurs (e.g., a user command is received toperform a defrost operation, or the time for a scheduled defrostoperation is reached), the plasma generator or the UV source may beconnected to the RF signal source, although the corresponding operationmay or may not be executing, as the system controller may be waiting fora next scheduled plasma/UV operation time to arrive according to apredetermined schedule. When the plasma operation or the UV operationcurrently is running, the system controller may send control signals tohalt operations of the plasma generator or UV source, and to cause theswitching arrangement to disconnect the plasma generator or UV sourcefrom the RF signal source. Alternatively, in some embodiments, thesystem controller may wait for the currently executing plasma/UVoperation to complete its current operation. In other embodiments, thesystem controller may allow the in-process operation to complete onlywhen the remaining time to completion is below a certain minimum timethreshold. For example, when there is no more than one minute (or someother time period) remaining in a plasma or UV operation, the systemcontroller may allow the operation to be completed before beginning adefrost operation. In yet other embodiments, the system controller maycontinue executing the in-process operation for an additional presetduration, such as 30 seconds (or some other time period), regardless ofwhether the operation would be completed after the preset duration.Alternatively, the system controller may stop the in-process operationonly when the operation has been running for a certain minimum time(such as 30 seconds or some other period), so that a device is notstopped immediately (or shortly) after starting. This may be useful, forexample, in case the device would experience excessive wear-and-tearfrom rapid transitions (power-ups and power-downs).

The interrupt (505) from default loop (502) to defrost/cooking loop(504) may feed certain information related to the defrost/cookingoperation to the system controller. This information may be based on,for example, entries input by a user through a user interface, and/orcalculations made by the system controller. Such information may includethe duration of a defrost or cooking operation, the type of food, thequantity of food, and so on. The defrost/cooking loop (504) begins, inblock 520, by the controller sending control signals to the switchingarrangement to disconnect the plasma generator or UV source, whicheveris connected. The system controller may then, in block 522, send controlsignals to the switching arrangement to connect the defroster to the RFsignal source, and in block 524, to set the output signal produced bythe RF signal source to a frequency required by the defroster. Thesystem controller may additionally set a defrost operation duration,which may have been input by the user or calculated based on the typeand quantify of food. The system controller may, in block 526, sendcontrol signals to tune the impedance as the defrost operation proceedsusing the variable impedance matching network (e.g., matching network260), as discussed above. Once the defrost operation has completed orotherwise has been interrupted, the system controller, in block 528,sends control signals to the switching arrangement to disconnect thedefrost system from the RF signal source and, in block 530, the processreturns to the default loop (502).

As discussed, embodiments of a multifunctional system include an RFexcitation signal source configured to produce an RF excitation signal,and a switching system or arrangement configured to provide the RFexcitation signal to one of multiple devices. The system may be embodiedin a standalone appliance, or may be incorporated into a larger system,such as commercial and industrial appliances (e.g., countertop andrefrigerator-type appliances that incorporate a hybrid defrost/airpurification/sterilization system). In certain embodiments, themultifunctional system may include components of a defrost system (e.g.,a matching network, an electrode, a grounded housing, and so on), a UVsource (including UV tubes), and a plasma generator (including plasmaelectrodes), all selectively coupled to a common RF signal source. Thesystem also may include a switching arrangement, which enables an RFsignal to be provided to the defrost components (when a defrostoperation is underway), to the UV source (when UV sterilization of theload is desired), or to the plasma generator (when air sterilization isdesired). For the sterilization processes, air from a cavity may becirculated through a separate purification chamber. The multifunctionalsystem can instead, in other embodiments, incorporate any set of devicesto be powered by an RF signal source.

The connecting lines shown in the various figures contained herein areintended to represent exemplary functional relationships and/or physicalcouplings between the various elements. It should be noted that manyalternative or additional functional relationships or physicalconnections may be present in an embodiment of the subject matter. Inaddition, certain terminology may also be used herein for the purpose ofreference only, and thus are not intended to be limiting, and the terms“first”, “second” and other such numerical terms referring to structuresdo not imply a sequence or order unless clearly indicated by thecontext.

The foregoing description refers to elements or nodes or features being“connected” or “coupled” together. As used herein, unless expresslystated otherwise, “connected” means that one element is directly joinedto (or directly communicates with) another element, and not necessarilymechanically. Likewise, unless expressly stated otherwise, “coupled”means that one element is directly or indirectly joined to (or directlyor indirectly communicates with) another element, and not necessarilymechanically. Thus, although the schematic shown in the figures depictone exemplary arrangement of elements, additional intervening elements,devices, features, or components may be present in an embodiment of thedepicted subject matter.

While at least one exemplary embodiment has been presented in theforegoing detailed description, it should be appreciated that a vastnumber of variations exist. It should also be appreciated that theexemplary embodiment or embodiments described herein are not intended tolimit the scope, applicability, or configuration of the claimed subjectmatter in any way. Rather, the foregoing detailed description willprovide those skilled in the art with a convenient road map forimplementing the described embodiment or embodiments. It should beunderstood that various changes can be made in the function andarrangement of elements without departing from the scope defined by theclaims, which includes known equivalents and foreseeable equivalents atthe time of filing this patent application.

EXAMPLES

Illustrative examples of the technologies disclosed herein are providedbelow. An embodiment of the technologies may include any one or more,and any combination of, the examples described below.

In an example 1, a system comprises: a housing including a first cavityconfigured to contain a load; a defrost system at least partiallydisposed in the first cavity, the defrost system being configured toreceive a first radio frequency (RF) signal at a first frequency todefrost the load within the first cavity; a first air treatment devicein fluid communication with the housing, the first air treatment devicebeing configured to receive a second RF signal at a second frequency,and to perform an air treatment process in response to the second RFsignal; an RF signal source having a power output for outputting RFsignals; a switching arrangement configured to selectively electricallyconnect the defrost system and the first air treatment device to thepower output of the RF signal source; and a controller configured to:cause the switching arrangement to electrically connect one of thedefrost system and the first air treatment device to the power output ofthe RF signal source, when the defrost system is electrically connectedto the power output of the RF signal source, cause the RF signal sourceto output the first RF signal at the first frequency, and when the firstair treatment device is electrically connected to the power output ofthe RF signal source, cause the RF signal source to output the second RFsignal at the second frequency.

An example 2 includes the subject matter of example 1, and furthercomprises: a second air treatment device in fluid communication with thehousing, the second air treatment device being configured to receive athird RF signal at a third frequency, and to perform an air treatmentprocess in response to the third RF signal, and wherein the controlleris further configured to cause the switching arrangement to electricallyconnect the second air treatment device to the power output of the RFsignal source.

An example 3 includes the subject matter of example 1 and/or 2, whereinthe first and second air treatment devices are selected from a plasmagenerator and an ultraviolet source.

An example 4 includes the subject matter of example 1, 2, and/or 3, andfurther comprises a variable impedance network having a first terminalcoupled to the switching arrangement and a second terminal coupled tothe defrost system.

An example 5 includes the subject matter of example 1, 2, 3, and/or 4,wherein the controller is configured to adjust an impedance of thevariable impedance network to match an impedance of the RF signal sourceto an impedance of the defrost system.

An example 6 includes the subject matter of example 1, 2, 3, 4, and/or5, wherein the controller is configured to cause the switchingarrangement to electrically connect the first air treatment device, andthe second air treatment device to the power output of the RF signalsource according to a predetermined schedule.

An example 7 includes the subject matter of example 1, 2, 3, 4, 5,and/or 6, and further comprises a user interface configured to transmita control signal to the controller in response to a user input, whereinthe controller is configured to cause the switching arrangement toelectrically connect one of the defrost system and the first airtreatment device to the power output of the RF power source in responseto the control signal.

An example 8 includes the subject matter of example 1, 2, 3, 4, 5, 6,and/or 7, and further comprises an air purification chamber in fluidcommunication with the housing and wherein the first air treatmentdevice is disposed within the air purification chamber.

An example 9 includes the subject matter of example 1, 2, 3, 4, 5, 6, 7,and/or 8, and further comprises a fan disposed within the airpurification chamber, the fan being connected to the controller and thecontroller being configured to activate the fan when the second RFsignal at the second frequency is supplied to the first air treatmentdevice.

In an example 10, a multifunctional radio frequency (RF) appliancecomprises: an RF signal source having a power output for supplying RFsignals at multiple output frequencies; a first device configured to bepowered by a first RF signal at a first frequency; a second deviceconfigured to be powered by a second RF signal at a second frequency; aswitching arrangement configured to selectively electrically connect thefirst device and the second device to the power output of the RF signalsource; and a controller configured to: cause the switching arrangementto electrically disconnect the first device from the power output of theRF signal source and electrically connect the second device to the poweroutput of the RF signal source, determine the second frequency of thesecond RF signal, and cause the RF signal source to supply the second RFsignal at the second frequency to the second device.

An example 11 includes the subject matter of example 10, and furthercomprises a variable impedance network having a first terminal connectedto the switching arrangement and a second terminal coupled to the seconddevice.

An example 12 includes the subject matter of example 10 and/or 11,wherein the controller is configured to adjust an impedance of thevariable impedance network to match an impedance of the RF power sourceto an impedance of the second device.

An example 13 includes the subject matter of example 10, 11, and/or 12,wherein the controller is configured to cause the switching arrangementto electrically disconnect the first device from the power output of theRF signal source and electrically connect the second device to the poweroutput of the RF signal source according to a predetermine schedule.

An example 14 includes the subject matter of example 10, 11, 12, and/or13, and further comprises a user interface configured to transmit acontrol signal to the controller in response to a user input and whereinthe controller is configured to cause the switching arrangement toelectrically disconnect the first device from the power output of the RFsignal source and electrically connect the second device to the poweroutput of the RF signal source in response to the control signal.

An example 15 includes the subject matter of example 10, 11, 12, 13,and/or 14, wherein the second device is selected from a plasma generatorand an ultraviolet source situated in an air purification chamber.

An example 16 includes the subject matter of example 10, 11, 12, 13, 14,and/or 15, and further comprises a fan disposed within the airpurification chamber, the fan being connected to the controller and thecontroller being configured to activate the fan when the second RFsignal at the second frequency is supplied to the second device.

In an example 17, a method comprises electrically connecting one of adefrost system, a plasma generator, and an ultraviolet generator to apower output of a radio frequency (RF) signal source, wherein: thedefrost system is configured to receive a first RF signal from the RFsignal source to defrost a load; the plasma generator is configured toreceive a second RF signal from the RF signal source to generate plasma;and the ultraviolet generator is configured to receive a third RF signalfrom the RF signal source to generate ultraviolet light; when thedefrost system is electrically connected to the power output of the RFsignal source, providing the defrost system with the first RF signal,when the plasma generator is electrically connected to the power outputof the RF signal source, providing the plasma generator with the secondRF signal, and when the ultraviolet generator is electrically connectedto the power output of the RF signal source, providing the ultravioletgenerator with the third RF signal.

An example 18 includes the subject matter of claim 17, and furtherincludes modifying an output impedance of the RF signal source based onan input impedance of the defrost system when the defrost system isbeing powered by the RF power source.

An example 19 includes the subject matter of claim 17 and/or 18, andfurther includes: powering the plasma generator and the ultravioletgenerator with the RF power source according to a predeterminedschedule; and exchanging air treated with plasma generated by the plasmagenerator and ultraviolet light generated by the ultraviolet generatorwith air outside of an air purification chamber.

An example 20 includes the subject matter of claim 17, 18, and/or 19,and further includes powering the plasma generator and ultravioletgenerator based on a preset schedule, and interrupting power to theplasma generator and the ultraviolet generator to power the defrostsystem upon receiving a user input or an interrupt.

What is claimed is:
 1. A method comprising: controlling, by acontroller, a switching arrangement to electrically connect one of adefroster and a first air treatment device to a power output of a radiofrequency (RF) signal source, wherein the defroster is configured toradiate electromagnetic energy into a cavity configured to contain aload in response to receiving a first RF signal from the RF signalsource, and wherein the first air treatment device is configured toreceive a second RF signal from the RF signal source, and to perform afirst air treatment process in response to the second RF signal; whenthe defroster is electrically connected to the power output of the RFsignal source, providing the defroster with the first RF signal; whenthe first air treatment device is electrically connected to the poweroutput of the RF signal source, providing the first air treatment devicewith the second RF signal.
 2. The method of claim 1, further comprising:controlling the switching arrangement to electrically connect one of thedefroster, the first air treatment device, and a second air treatmentdevice to the power output of the RF signal source, wherein the secondair treatment device is configured to receive a third RF signal from theRF signal source, and to perform a second air treatment process inresponse to the third RF signal; and when the second air treatmentdevice is electrically connected to the power output of the RF signalsource, providing the second air treatment device with the third RFsignal.
 3. The method of claim 1, further including modifying an outputimpedance of the RF signal source based on an input impedance of thedefroster when the defroster is being powered by the RF power source. 4.The method of claim 1, wherein the first air treatment device is aplasma generator configured to generate plasma in response to the secondRF signal.
 5. The method of claim 4, further including: powering theplasma generator with the RF signal source according to a predeterminedschedule; and exchanging air treated with plasma generated by the plasmagenerator with air outside of an air purification chamber.
 6. The methodof claim 1, wherein the first air treatment device is an ultravioletgenerator configured to generate ultraviolet light in response to thesecond RF signal
 7. The method of claim 6, further including: poweringthe ultraviolet generator with the RF signal source according to apredetermined schedule; and exchanging air treated with ultravioletlight generated by the ultraviolet generator with air outside of an airpurification chamber.
 8. The method of claim 1, further comprising:powering the first air treatment device based on a preset schedule, andinterrupting power to the first air treatment device to power thedefroster upon receiving a user input or an interrupt.
 9. The method ofclaim 1, further comprising: transmitting, by a user interface, acontrol signal to the controller in response to a user input made usingthe user interface, wherein the controller is configured to cause theswitching arrangement to electrically connect one of the defroster andthe first air treatment device to the power output of the RF signalsource in response to the control signal.
 10. The method of claim 1,further comprising: activating a fan when the second RF signal issupplied to the first air treatment device.
 11. A multifunctional radiofrequency (RF) appliance comprising: an RF signal source having a poweroutput for supplying RF signals at multiple output frequencies; a firstdevice configured to be powered by a first RF signal at a firstfrequency; a second device configured to be powered by a second RFsignal at a second frequency; a switching arrangement configured toselectively electrically connect the first device and the second deviceto the power output of the RF signal source; and a controller configuredto: cause the switching arrangement to electrically disconnect the firstdevice from the power output of the RF signal source and electricallyconnect the second device to the power output of the RF signal source,and cause the RF signal source to supply the second RF signal at thesecond frequency to the second device.
 12. The multifunctional RFappliance of claim 11, further comprising a variable impedance networkhaving a first terminal connected to the switching arrangement and asecond terminal coupled to the second device.
 13. The multifunctional RFappliance of claim 12, wherein the controller is configured to adjust animpedance of the variable impedance network to match an impedance of theRF signal source to an impedance of the second device.
 14. Themultifunctional RF appliance of claim 11, wherein the controller isconfigured to cause the switching arrangement to electrically disconnectthe first device from the power output of the RF signal source andelectrically connect the second device to the power output of the RFsignal source according to a predetermine schedule.
 15. Themultifunctional RF appliance of claim 11, further comprising a userinterface configured to transmit a control signal to the controller inresponse to a user input and wherein the controller is configured tocause the switching arrangement to electrically disconnect the firstdevice from the power output of the RF signal source and electricallyconnect the second device to the power output of the RF signal source inresponse to the control signal.
 16. The multifunctional RF appliance ofclaim 11, further comprising: a housing including a cavity configured tocontain a load, wherein the first device is a first air treatment devicein fluid communication with the housing, and the second device is adefroster having an electrode at least partially disposed in the cavity.17. The multifunctional RF appliance of claim 16, wherein the firstdevice is selected from a plasma generator and an ultraviolet sourcesituated in an air purification chamber.
 18. The multifunctional RFappliance of claim 17, further comprising a fan disposed within the airpurification chamber, the fan being connected to the controller and thecontroller being configured to activate the fan when the first RF signalat the first frequency is supplied to the first device.
 19. Themultifunctional RF appliance of claim 16, further comprising: a secondair treatment device in fluid communication with the housing, the secondair treatment device being configured to receive a third RF signal at athird frequency, and to perform an air treatment process in response tothe third RF signal, and wherein the controller is further configured tocause the switching arrangement to electrically connect the second airtreatment device to the power output of the RF signal source.